Solids, Liquids and Gases

Question 1

What is pressure difference?

Answer 1

Pressure difference is the difference in pressure between two points in a liquid or a gas.

Question 2

What is the equation for pressure difference?

Answer 2

Pressure difference = height x density x g

Question 3

What is pressure measured in?

Answer 3

Pascals (N/m2)

Question 4

What are the three things you need to mention when describing the arrangement of particles in different states of matter?

Answer 4

• The strength of the forces of attraction between particles
• How much energy the particles have
• Wether their arrangement is fixed and regular

Question 5

How can particles evaporate from a liquid at temperatures much lower than the liquid’s boiling point?

Answer 5

Particles near the surface fo the liquid can escape and become gas particles if:

• The particles are travelling in the right direction to escape a liquid
• The particles have enough kinetic energy to overcome the forces of attraction from other particles in the liquid.

Question 6

It is the fastest particles that are most likely to evaporate from a liquid. When they do, what happens?
Why is it useful?

Answer 6

• The average speed and kinetic energy of the remaining particles in the liquid decreases
• This decrease in the average particle energy means the temperature of the remaining liquid falls
• This cooling effect can be really useful. For example, when you sweat after you’ve got too hot the water from the sweat on your skin evaporates and this cools you down.

Question 7

What is brownian motion?

Answer 7

Large heavy particles (e.g. smoke) can be moved by smaller, lighter particles travelling at high speeds (e.g. air).
This is why smoke particles in the air appear to move randomly when you observe them in the lab.

Question 8

What is absolute zero? What is it in degrees or kelvins?

Answer 8

As cold as something can possibly get - atoms have as little kinetic energy as it is possible to get.
It is -273 degrees and 0 kelvins.

Question 9

How do you convert between Kelvins and degrees?

Answer 9

Kelvins to degrees: subtract 273

Degrees to Kelvins: add 273

Question 10

what is the relationship between pressure and volume at a constant temperature?

Answer 10

P1 x V1 = P2 x V2

Question 11

What is the relationship between pressure and temperature at a constant volume?

Answer 11

P1/ T1 = P2/T2